Raisa Energy LLC, a Denver-based oil-and-gas company backed by private equity firm EnCap Investments LP, closed the first such offering in September and several others are planned before the end of the year, said people familiar with the transactions. The bonds will pay nearly 6% interest on the best quality wells, the people said, with higher rates on riskier assets. SHARE YOUR THOUGHTS How can shale companies make their asset-backed securities a little more secure for investors? Join the conversation below. The investments are drawing attention from insurance companies, large money managers and other traditional investors of asset-backed securities. They represent a new avenue for shale companies as the industry’s traditional investors sour on the sector following years of disappointing returns. While similar in structure to securities backed by mortgages and auto loans, the securities pose potential risks because projecting the long-term output from shale wells remains an inexact […]